Magnetic properties of iron oxide nanoclusters within microdomains of block copolymers

被引：136

作者：

Sohn, BH

Cohen, RE ^{[1
]}

Papaefthymiou, GC

机构：

[1] MIT, Dept Chem Engn, Cambridge, MA 02139 USA

[2] MIT, Francis Bitter Natl Magnet Lab, Cambridge, MA 02139 USA

来源：

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS | 1998年 / 182卷 / 1-2期

基金：

美国国家科学基金会;

关键词：

nanoclusters; iron oxide; block copolymers; superparamagnetism; Mossbauer spectroscopy;

D O I：

10.1016/S0304-8853(97)00675-6

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

The magnetic properties of gamma-Fe2O3 nanoclusters grown within the microdomains of optically transparent block copolymer films were investigated. SQUID magnetometry and Fe-57 Mossbauer spectroscopy were employed with characteristic measurement times of 100 s and 10(-s) s, respectively. The observed magnetism of the ca. 5 nm diameter particles was dominated by quantum-size effects, collective magnetic excitations, and superparamagnetic relaxation processes associated with the sub-magnetic domain gamma-Fe2O3 nanoclusters. The combination of these two techniques allowed determination of the values of the magnetic anisotropy constant (K = 1.58 x 10(5) J/m(3)) and the pre-exponential factor (tau(0) = 4.2 x 10(-12) s) which determine the magnetic behavior of the nanocomposites. At low temperatures, the nanocomposite films exhibited hysteresis with the saturated coercivity, H-c(0), equal to 530 Oe. (C) 1998 Elsevier Science B.V. All rights reserved.

引用

页码：216 / 224

页数：9

共 66 条

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